What is a Shore A Hardness and why is it important?
What is a Shore durometer?
The Shore durometer is an instrument used for measuring the material’s hardness, generally rubbers, elastomers, and polymers. The Shore A hardness measurement is called ‘’durometer’’. Tests are carried out on cured rubber according to ASTM D2240, and on a complete O Ring according to ASTM D1414. Durometer instrument comprises of a toughened steel rod with a bevelled cone at the tip. The steel rod is spring-loaded and activates a gauge with a scale between 1 and 100. The test sample is positioned straight under the bevelled cone. The instrument is then pressed against the material until the flat metal plate in the bottom is levelled with the elastomer sample. In its scale, higher numbers specify a more superior resistance to indentation and therefore harder materials. So, the less the cone deforms the sample, the higher material hardness. Differently, lower numbers on the durometer scale indicate lesser resistance to indentation and softer materials, so the more the cone deforms the sample, the lesser the hardness of the material.
What is a Shore A Hardness?
An O Ring seal is a rubber moulded circular cross-section ring, which is used to avert the forfeiture of a gas or fluid in a housing. It is the most fundamental and most extensively used kind of seal available. Obtaining the right hardness is one of the key elements of getting a correct O Ring for the required installation. The Hardness of elastomer O Rings is measured by the Shore A durometer mentioned above. The higher the durometer, the harder the material. Commonly, 70-durometer hardness presents the superior blend of properties for the majority of O Ring installations, therefore it should be used whenever possible.
Why is Shore A Hardness important?
O Rings are arguably the best seal for a number of installations due to them being the simplest and most easily acquired type of seal. One of the most crucial factors to consider is the hardness of an elastomeric material. However, some installations may require a softer material, for example when sealing a fragile hardware such as thin plastic or in order to minimise insertion force. Shore A Hardness is a conventional test for elastomers.
Shore hardness Comparison Chart:
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